Radium Radium is a chemical element; it has chemical symbol, symbol Ra and atomic number 88. It is the sixth element in alkaline earth metal, group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, ...

(₈₈Ra) has no stable or nearly stable

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s, and thus a

standard atomic weight The standard atomic weight of a chemical element (symbol ''A''r°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, ...

cannot be given. The longest lived, and most common, isotope of radium is ²²⁶Ra with a half-life of . ²²⁶Ra occurs in the

decay chain In nuclear science a decay chain refers to the predictable series of radioactive disintegrations undergone by the nuclei of certain unstable chemical elements. Radioactive isotopes do not usually decay directly to stable isotopes, but rather ...

of ²³⁸U (often referred to as the radium series). Radium has 34 known isotopes from ²⁰¹Ra to ²³⁴Ra. In the early history of the study of radioactivity, the different natural isotopes of radium were given different names, as it was not until

Frederick Soddy Frederick Soddy FRS (2 September 1877 – 22 September 1956) was an English radiochemist who explained, with Ernest Rutherford, that radioactivity is due to the transmutation of elements, now known to involve nuclear reactions. He also pr ...

's scientific career in the early 1900s that the concept of isotopes was realized. In this scheme, Ra was named actinium X (AcX), Ra thorium X (ThX), Ra radium (Ra), and Ra mesothorium 1 (MsTh). When it was realized that all of these are isotopes of the same element, many of these names fell out of use, and "radium" came to refer to all isotopes, not just Ra, though mesothorium 1 in particular was still used for some time, with a footnote explaining that it referred to Ra. Some of radium-226's decay products received historical names including "radium", ranging from radium to radium , with the letter indicating approximately how far they were down the chain from their parent Ra. In 2013 it was discovered that the nucleus of radium-224 is pear-shaped. This was the first discovery of an asymmetrical nucleus.

List of isotopes

, -id=Radium-201 , ²⁰¹Ra , , style="text-align:right" , 88 , style="text-align:right" , 113 , 201.012815(22) , 20(30) ms , α , ¹⁹⁷Rn , (3/2−) , , -id=Radium-201m , style="text-indent:1em" , ^201mRa , , colspan="3" style="text-indent:2em" , 263(26) keV , 6(5) ms , α , ¹⁹⁷Rn , 13/2+ , , -id=Radium-202 , ²⁰²Ra , , style="text-align:right" , 88 , style="text-align:right" , 114 , 202.009742(16) , 4.1(11) ms , α , ¹⁹⁸Rn , 0+ , , -id=Radium-203 , ²⁰³Ra , , style="text-align:right" , 88 , style="text-align:right" , 115 , 203.009234(10) , 36(13) ms , α , ¹⁹⁹Rn , 3/2− , , -id=Radium-203m , style="text-indent:1em" , ^203mRa , , colspan="3" style="text-indent:2em" , 246(14) keV , 25(5) ms , α , ¹⁹⁹Rn , 13/2+ , , -id=Radium-204 , ²⁰⁴Ra , , style="text-align:right" , 88 , style="text-align:right" , 116 , 204.0065069(96) , 60(9) ms , α (99.7%) , ²⁰⁰Rn , 0+ , , -id=Radium-205 , ²⁰⁵Ra , , style="text-align:right" , 88 , style="text-align:right" , 117 , 205.006231(24) , 220(50) ms , α , ²⁰¹Rn , 3/2− , , -id=Radium-205m , style="text-indent:1em" , ^205mRa , , colspan="3" style="text-indent:2em" , 263(25) keV , 180(50) ms , α , ²⁰¹Rn , 13/2+ , , -id=Radium-206 , ²⁰⁶Ra , , style="text-align:right" , 88 , style="text-align:right" , 118 , 206.003828(19) , 0.24(2) s , α , ²⁰²Rn , 0+ , , -id=Radium-207 , rowspan=2, ²⁰⁷Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 119 , rowspan=2, 207.003772(63) , rowspan=2, 1.38(18) s , α (86%) , ²⁰³Rn , rowspan=2, 5/2−# , rowspan=2, , - , β⁺ (14%) , ²⁰⁷Fr , -id=Radium-207m , rowspan=2 style="text-indent:1em" , ^207mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 560(60) keV , rowspan=2, 57(8) ms , IT (85#%) , ²⁰⁷Ra , rowspan=2, 13/2+ , rowspan=2, , - , α (?%) , ²⁰³Rn , -id=Radium-208 , rowspan=2, ²⁰⁸Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 120 , rowspan=2, 208.0018550(97) , rowspan=2, 1.110(45) s , α (87%) , ²⁰⁴Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (13%) , ²⁰⁸Fr , -id=Radium-208m , style="text-indent:1em" , ^208mRa , , colspan="3" style="text-indent:2em" , 2147.4(4) keV , 263(17) ns , IT , ²⁰⁸Ra , (8+) , , -id=Radium-209 , ²⁰⁹Ra , , style="text-align:right" , 88 , style="text-align:right" , 121 , 209.0019949(62) , 4.71(8) s , α (90%) , ²⁰⁵Rn , 5/2− , , -id=Radium-209m , rowspan=2 style="text-indent:1em" , ^209mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 882.4(7) keV , rowspan=2, 117(5) μs , α (90%) , ²⁰⁵Rn , rowspan=2, 13/2+ , rowspan=2, , - , β⁺ (10%) , ²⁰⁹Fr , -id=Radium-210 , ²¹⁰Ra , , style="text-align:right" , 88 , style="text-align:right" , 122 , 210.0004754(99) , 4.0(1) s , α , ²⁰⁶Rn , 0+ , , -id=Radium-210m , style="text-indent:1em" , ^210mRa , , colspan="3" style="text-indent:2em" , 2050.9(7) keV , 2.29(3) μs , IT , ²¹⁰Ra , 8+ , , -id=Radium-211 , ²¹¹Ra , , style="text-align:right" , 88 , style="text-align:right" , 123 , 211.0008930(53) , 12.6(12) s , α , ²⁰⁷Rn , 5/2− , , -id=Radium-211m , style="text-indent:1em" , ^211mRa , , colspan="3" style="text-indent:2em" , 1198.1(8) keV , 9.5(3) μs , IT , ²¹¹Ra , 13/2+ , , -id=Radium-212 , rowspan=2, ²¹²Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 124 , rowspan=2, 211.999787(11) , rowspan=2, 13.0(2) s , α (?%) , ²⁰⁸Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (?%) , ²¹²Fr , -id=Radium-212m1 , style="text-indent:1em" , ^212m1Ra , , colspan="3" style="text-indent:2em" , 1958.4(20) keV , 9.3(9) μs , IT , ²¹²Ra , 8+ , , -id=Radium-212m2 , style="text-indent:1em" , ^212m2Ra , , colspan="3" style="text-indent:2em" , 2613.3(20) keV , 0.85(13) μs , IT , ²¹²Ra , 11− , , -id=Radium-213 , rowspan=2, ²¹³Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 125 , rowspan=2, 213.000371(11) , rowspan=2, 2.73(5) min , α (87%) , ²⁰⁹Rn , rowspan=2, 1/2− , rowspan=2, , - , β⁺ (13%) , ²¹³Fr , -id=Radium-213m , rowspan=2 style="text-indent:1em" , ^213mRa , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 1768(4) keV , rowspan=2, 2.20(5) ms , IT (99.4%) , ²¹³Ra , rowspan=2, (17/2−) , rowspan=2, , - , α (0.6%) , ²⁰⁹Rn , -id=Radium-214 , rowspan=2, ²¹⁴Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 126 , rowspan=2, 214.0000996(56) , rowspan=2, 2.437(16) s , α (99.94%) , ²¹⁰Rn , rowspan=2, 0+ , rowspan=2, , - , β⁺ (0.059%) , ²¹⁴Fr , -id=Radium-214m1 , style="text-indent:1em" , ^214m1Ra , , colspan="3" style="text-indent:2em" , 1819.7(18) keV , 118(7) ns , IT , ²¹⁴Ra , 6+ , , -id=Radium-214m2 , rowspan=2 style="text-indent:1em" , ^214m2Ra , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 1865.2(18) keV , rowspan=2, 67.3(15) μs , IT (99.91%) , ²¹⁴Ra , rowspan=2, 8+ , rowspan=2, , - , α (0.09%) , ²¹⁰Rn , -id=Radium-214m3 , style="text-indent:1em" , ^214m3Ra , , colspan="3" style="text-indent:2em" , 2683.2(18) keV , 295(7) ns , IT , ²¹⁴Ra , 11− , , -id=Radium-214m4 , style="text-indent:1em" , ^214m4Ra , , colspan="3" style="text-indent:2em" , 3478.4(18) keV , 279(4) ns , IT , ²¹⁴Ra , 14+ , , -id=Radium-214m5 , style="text-indent:1em" , ^214m5Ra , , colspan="3" style="text-indent:2em" , 4146.8(18) keV , 225(4) ns , IT , ²¹⁴Ra , 17− , , -id=Radium-214m6 , style="text-indent:1em" , ^214m6Ra , , colspan="3" style="text-indent:2em" , 6577.0(18) keV , 128(4) ns , IT , ²¹⁴Ra , (25−) , , -id=Radium-215 , ²¹⁵Ra , , style="text-align:right" , 88 , style="text-align:right" , 127 , 215.0027182(77) , 1.669(9) ms , α , ²¹¹Rn , 9/2+# , , -id=Radium-215m1 , style="text-indent:1em" , ^215m1Ra , , colspan="3" style="text-indent:2em" , 1877.8(3) keV , 7.31(13) μs , IT , ²¹⁵Ra , (25/2+) , , -id=Radium-215m2 , style="text-indent:1em" , ^215m2Ra , , colspan="3" style="text-indent:2em" , 2246.9(4) keV , 1.39(7) μs , IT , ²¹⁵Ra , (29/2−) , , -id=Radium-215m3 , style="text-indent:1em" , ^215m3Ra , , colspan="3" style="text-indent:2em" , 3807(50)# keV , 555(10) ns , IT , ²¹⁵Ra , (43/2−) , , -id=Radium-216 , rowspan=2, ²¹⁶Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 128 , rowspan=2, 216.0035335(86) , rowspan=2, 172(7) ns , α , ²¹²Rn , rowspan=2, 0+ , rowspan=2, , - , EC (<1×10⁻⁸%) , ²¹⁶Fr , -id=Radium-217 , ²¹⁷Ra , , style="text-align:right" , 88 , style="text-align:right" , 129 , 217.0063227(76) , 1.95(12) μs , α , ²¹³Rn , (9/2+) , , -id=Radium-218 , ²¹⁸Ra , , style="text-align:right" , 88 , style="text-align:right" , 130 , 218.007134(11) , 25.91(14) μs , α , ²¹⁴Rn , 0+ , , -id=Radium-219 , ²¹⁹Ra , , style="text-align:right" , 88 , style="text-align:right" , 131 , 219.0100847(73) , 9(2) ms , α , ²¹⁵Rn , (7/2)+ , , -id=Radium-219m , style="text-indent:1em" , ^219mRa , , colspan="3" style="text-indent:2em" , 16.7(8) keV , 10(3) ns , α , ²¹⁵Rn , (11/2)+ , , -id=Radium-220 , ²²⁰Ra , , style="text-align:right" , 88 , style="text-align:right" , 132 , 220.0110275(82) , 18.1(12) ms , α , ²¹⁶Rn , 0+ , , -id=Radium-221 , rowspan=2, ²²¹Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 133 , rowspan=2, 221.0139173(05) , rowspan=2, 25(4) s , α , ²¹⁷Rn , rowspan=2, 5/2+ , rowspan=2, TraceIntermediate decay product of ²³⁷Np , - , CD (1.2×10⁻¹⁰%)Lightest known nuclide to undergo

cluster decay Cluster decay, also named heavy particle radioactivity, heavy ion radioactivity or heavy cluster decay," is a rare type of nuclear decay in which an atomic nucleus emits a small "cluster" of neutrons and protons, more than in an alpha particle, ...

, ²⁰⁷Pb
¹⁴C , -id=Radium-222 , rowspan=2, ²²²Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 134 , rowspan=2, 222.0153734(48) , rowspan=2, 33.6(4) s , α , ²¹⁸Rn , rowspan=2, 0+ , rowspan=2, , - , CD (3.0×10⁻⁸%) , ²⁰⁸Pb
¹⁴C , - , rowspan=2, ²²³RaUsed for treating bone cancer , rowspan=2, Actinium X , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 135 , rowspan=2, 223.0185006(22) , rowspan=2, 11.4352(10) d , α , ²¹⁹Rn , rowspan=2, 3/2+ , rowspan=2, TraceIntermediate

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( d ...

of ²³⁵U , - , CD (8.9×10⁻⁸%) , ²⁰⁹Pb
¹⁴C , -id=Radium-224 , rowspan=2, ²²⁴Ra , rowspan=2, Thorium X , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 136 , rowspan=2, 224.0202104(19) , rowspan=2, 3.6316(14) d , α , ²²⁰Rn , rowspan=2, 0+ , rowspan=2, TraceIntermediate decay product of ²³²Th , - , CD (4.0×10⁻⁹%) , ²¹⁰Pb
¹⁴C , -id=Radium-225 , rowspan=2, ²²⁵Ra , rowspan=2, , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 137 , rowspan=2, 225.0236105(28) , rowspan=2, 14.82(19) d , β⁻ , ²²⁵Ac , rowspan=2, 1/2+ , rowspan=2, TraceIntermediate decay product of ²³⁷Np , - , α (.0026%) , ²²¹Rn , - , rowspan=2, ²²⁶Ra , rowspan=2, RadiumSource of element's name , rowspan=2 style="text-align:right" , 88 , rowspan=2 style="text-align:right" , 138 , rowspan=2, 226.0254082(21) , rowspan=2, 1600(7) y , α , ²²²Rn , rowspan=2, 0+ , rowspan=2, TraceIntermediate decay product of ²³⁸U , - , CD (2.6×10⁻⁹%) , ²¹²Pb
¹⁴C , -id=Radium-227 , ²²⁷Ra , , style="text-align:right" , 88 , style="text-align:right" , 139 , 227.0291762(21) , 42.2(5) min , β⁻ , ²²⁷Ac , 3/2+ , , -id=Radium-228 , ²²⁸Ra , Mesothorium 1 , style="text-align:right" , 88 , style="text-align:right" , 140 , 228.0310686(21) , 5.75(3) y , β⁻ , ²²⁸Ac , 0+ , Trace , -id=Radium-229 , ²²⁹Ra , , style="text-align:right" , 88 , style="text-align:right" , 141 , 229.034957(17) , 4.0(2) min , β⁻ , ²²⁹Ac , 5/2+ , , -id=Radium-230 , ²³⁰Ra , , style="text-align:right" , 88 , style="text-align:right" , 142 , 230.037055(11) , 93(2) min , β⁻ , ²³⁰Ac , 0+ , , -id=Radium-231 , ²³¹Ra , , style="text-align:right" , 88 , style="text-align:right" , 143 , 231.041027(12) , 104(1) s , β⁻ , ²³¹Ac , (5/2+) , , -id=Radium-231m , style="text-indent:1em" , ^231mRa , , colspan="3" style="text-indent:2em" , 66.21(9) keV , ~53 μs , IT , ²³¹Ra , (1/2+) , , -id=Radium-232 , ²³²Ra , , style="text-align:right" , 88 , style="text-align:right" , 144 , 232.0434753(98) , 4.0(3) min , β⁻ , ²³²Ac , 0+ , , -id=Radium-233 , ²³³Ra , , style="text-align:right" , 88 , style="text-align:right" , 145 , 233.0475946(92) , 30(5) s , β⁻ , ²³³Ac , 1/2+# , , -id=Radium-234 , ²³⁴Ra , , style="text-align:right" , 88 , style="text-align:right" , 146 , 234.0503821(90) , 30(10) s , β⁻ , ²³⁴Ac , 0+ ,

Actinides vs fission products

References

* Isotope masses from: ** * Half-life, spin, and isomer data selected from the following sources. ** ** **

Notes

{{Authority control Radium